1. Field of the Invention
The present invention relates to a welding apparatus for welding steel billets, etc. More particularly, it relates to a welding apparatus which is used in a continuous rolling operation.
2. Description of the Prior Art
Referring to FIGS. 5 and 6, the conventional welding apparatus for welding steel billets etc. will be illustrated.
In FIGS. 5 and 6, the reference numeral (101) designates a main frame which is a base for holding the body of the welding apparatus and is suspended on a truck (not shown); (102) designates a C type or bridge type press frame in the stationary side which is fixed on the main frame (101); (103) designates a C type or bridge type press frame in the moving side which is fitted to a slide frame (104) sliding in guides (105) fixed on both sides of the main frame (101); (106) designates a clamp cylinder assembled in the press frames (102), (103). The clamp cylinder has the function to forcibly clamp a workpiece (110) positioned on a lower electrode (108') fixed on the lower part of the press frames (102), (103) or the upper part of the main frame (101) between the lower electrode and an upper electrode (108) connected to the cylinder rod. The reference numeral (107) designates an up-set cylinder which is connected to the main frame (101). The up-set cylinder (107) is used for moving the workpiece (110) clamped by the electrodes on the fixed press frame (102) under pushing by the workpiece (110') clamped by the electrodes on the moving frame (103) for welding the workpieces clamped between the upper and lower electrodes (108), (108') by feeding a desired current from a transformer (109) assembled in the main frame (101) to the electrodes (108), (108').
In order to weld hot steel billets in the rolling line by the conventional welding apparatus, the welding should be carried out under travelling the welding apparatus held on the truck. The following disadvantages have been found when the conventional welding apparatus is used.
(1) The lower electrode is not sunk, whereby the lower surface of the workpiece is contacted with the electrode during the time for inserting and taking out the workpiece to cause trouble.
(2) The electrode pressing force of the clamp cylinder is applied not only to the press frames (102), (103) but also to the main frame (101), whereby the structural strength of the frames being proportional to the electrode pressing force is required not only for the press frames but also for the other frames.
(3) The center of the workpiece and the center of the upset cylinder and the central axis of the guide are not easily positioned on one line (linear), whereby the structural strength of the main frame being proportional to the up-setting force is required.
(4) The line of the circuit between the transformer and the electrodes is long, whereby a transformer having a large capacity is required.
(5) The weight and size of the welding apparatus should be large in order to satisfy the requirements (1) to (4). It is difficult to minimize the width of the welding apparatus, whereby it is difficult to use the conventional welding apparatus in a rolling system having plural lines.
(6) The parts of the welding apparatus below the workpieces are large, whereby it is not easy to remove the fallen scales and the flush sputters, etc.